This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-341048, filed Nov. 30, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to an information processing apparatus such as a small-sized portable terminal, which has a display device with a backlight.
In recent years, information processing apparatuses have been developed, which are provided with cameras and are capable of acquiring a color image, storing it as a file, or sending it along with an e-mail. In particular, if this type of information processing apparatus is constructed as a battery-powered portable device, the information processing apparatus can be carried to a desired place and a color image can be acquired there.
A color image acquired by the camera has a lower contrast than a computer-graphics (CG) image. Thus, the color image acquired by the camera becomes easier to view, if it is displayed on a backlight-equipped display device with a backlight luminance increased. However, if the backlight luminance is increased, the power consumption increases. In the case of a battery-powered information processing apparatus, lower power consumption is required in order to increase a time period in which stable operations are ensured. In addition, a luminance control for a backlight that consumes relatively high power is also required. In particular, in the case of a small-sized information processing apparatus, the problem of power consumption is serious since it cannot be equipped with a high-capacity battery.
Moreover, in the case of a battery-powered information processing apparatus including a display device with a backlight, the ratio of power consumption of the backlight to the total power consumption of the apparatus is high. When the remaining power of the battery has decreased, the power consumption of the backlight affects the stability in operation of the apparatus.
An object of the present invention is to provide an information processing apparatus, the power consumption of which can be reduced by controlling the luminance of a backlight, without degrading operability of the apparatus.
Another object of the invention is to provide a battery-powered information processing apparatus having a display device with a backlight, which can be stably operated even where the remaining power of the battery has decreased.
According to an aspect of the present invention, there is provided an information processing apparatus. The apparatus comprises a display device for displaying information; backlight means for emitting a backlight to the display device, the backlight having various luminance levels; discrimination means for discriminating a display content of information displayed on the display device; and screen control means for altering a luminance of the backlight in accordance with the display content discriminated by the discrimination means.
With this structure, the luminance of the backlight can be altered in accordance with the display content on the display device. Where it is not necessary that the display content on the display device be presented to the user in such a way that the display content may easily and clearly viewed by the user, the luminance of the backlight may be decreased to save power consumption.
It is preferable that the screen control means increases the luminance of the backlight where the discrimination means has determined that an image is to be displayed on the display device.
The feature of the camera image is the presence of medium colors on a most part of the image, with a neutral-level (not high) chroma and brightness. Accordingly, the luminance of the backlight is increased to make the camera image easier to view.
It is preferable that the information processing apparatus further comprises transmission/reception means for transmitting/receiving an e-mail. The screen control means decreases the luminance of the backlight where the discrimination means has determined that a screen image indicative of a state in which the e-mail is being transmitted is to be displayed on the display device.
While the e-mail is being transmitted, display is made only to show a progress of the operation to the user, and the user is not permitted to perform any operation with reference to the display screen. Accordingly, only if a display of the operation state can be visually recognized on the display device, some difficulty in viewing the display content will pose no problem. Thus, the luminance of the backlight is decreased.
The information processing apparatus may further comprise first determination means for determining whether a predetermined time period has passed since latest input of data by means of input means. When the first determination means has determined that the predetermined time period has passed, the screen control means may decrease the luminance of the backlight.
The information processing apparatus may further comprise second determination means for determining whether a predetermined time period has passed since a latest operation of camera operation means. When the second determination means has determined that the predetermined time period has passed, the screen control means may decreases the luminance of the backlight.
Where no data has been input or the operation section has not been activated for a predetermined time period, it is probable that the user is not currently viewing the display device and in this case power is wasted if the luminance of the backlight is maintained at high level. Accordingly, if a predetermined time has passed, the luminance of the backlight may be lowered to save power consumption.
The information processing apparatus may be driven by a battery and further comprise monitor means for monitoring a state of the battery. It is preferable that the monitor means monitors a remaining power of the battery and the screen control means decreases the luminance of the backlight when the monitored remaining power of the battery has decreased to a predetermined value or less.
In some cases, when the remaining power of the battery has decreased, an increase in operation time of the information processing apparatus is preferable at the cost of ease in viewing the screen. In such cases, the operation time of the information processing apparatus is increased by lowering the luminance of the backlight.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.